snippet: Updated all snippet tags

Ensure all src C++ headers which have corresponding C++ examples have
doxygen tags which point to those examples.  Some were missing, some
were invalid, some needed to be updated to match the new example names.

Signed-off-by: Noel Eck <noel.eck@intel.com>

src/mpu9150/ak8975.hpp

@@ -48,7 +48,7 @@ namespace upm {
    * coupled with another device (such as the mcu9150 9-axis motion
    * sensor).
    *
-   * @snippet ak8975.cxx Interesting
+   * @snippet mpu9150-ak8975.cxx Interesting
    */
   class AK8975 {
   public: